Rotary expansible drill bits



July 10, 1956 A. w. KAMMERER, JR 2,754,088

ROTARY EXPANSIBLE DRILL BITS Filed Nov. 23, 1953 AQCHEQ 2,754,088 ROTARY EXPANSlBLE DRILL BITS Archer W. Kammerer, Jr., Fullerton, Califi, assignor, by direct and mesne assignments, to Rotary Oil Tool Com- Fairy, Huntington Park, Califi, a corporation of Caliornla Application November 23, 1953, Serial No. 393,771 8 Claims. (Cl. 255-76) The present invention relates to rotary drill bits, and more particularly to bits of the expansible type for drilling or reaming bore holes below well casing to a larger diameter than the inside diameter of the casing itself.

Expansible drill bits have been used for enlarging or drilling well bores to greater diameters than the inside diameters of strings of casing through which the bits are capable of passing. In the patent to Archer W. Kammerer, 2,545,036, a telescoping mandrel in the body of the tool locks the bit cutters in their outwardly expanded position, by moving the mandrel longitudinally in the body. However, elevation of the mandrel, or the elimination of drilling weight on the tool, causes the mandrel to be removed from its locking position in the body, which, under some operation conditions, is not desirable.

Accordingly, it is an object of the present invention to provide an improved expansible drill bit, in which upward movement of the mandrel telescopically arranged in the body of the bit does not effect a removal of the man drel from its locking position holding the cutters outwardly expanded. Despite this fact, the mandrel is still movable with respect to the body to shift the mandrel to a cutter unlocking position whenever the cutters are to be shifted from their expanded position to a retracted position.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a longitudinal section through an embodiment of the invention disposed in a well bore, with the cutters and other parts in their initial retracted positions;

Fig. 2 is a view similar to Fig. 1, disclosing the cutters locked in their fully outwardly expanded positions.

The expansible drill bit disclosed in the drawings is specifically of the kind shown in the above referred to patent. The rotary drill bit it attached to a string of drill pipe A by means of which it is lowered through a well casing B in a well bore C to a point below the casing shoe D at which the diameter of the bore hole is to be enlarged. The drilling tool may have a pilot bit 10 at its lower end for centering the tool in a hole that may have already been drilled, or for drilling the central portion of a new hole in the absence of a pre-existing hole. The main portion of the bit is capable of enlarging the bore hole by producing and operating upon a formation shoulder E, as hereinafter described.

The upper end of the bit consists of a driving mandrel 11 having an upper pin 12 threadedly connected to a sub 13 forming the lower end of the drill pipe string A. This mandrel 11 includes an upper Kelly or drill stem nited States Patent 0 Patented July 10, 1956 member 14 slidably splined to the main body 15 of the bit. As described specifically in the above Patent 2,545,036, the exterior 14a of the Kelly may be non-circular or hexagonally shaped for telescopic reception in a companion non-circular or hexagonal socket 15a formed in the body 15. The mandrel 11 has a limited range of longitudinal movement within the body, its upward movement being limited by engagement of an external shoulder 16 on the Kelly portion 14 with a retainer ring 17 at the upper end of the body, which may be secured to the latter by the use of welding material 18.

The body has a plurality of expansible parts mounted on it, comprising cutter supporting members 19 pivotally mounted in body slots 20 on hinge pins 21 suitably welded to the body. Each cutter supporting member 19 consists of a depending leg 22 having a bearing supporting pin 23 inclined inwardly and downwardly and on which a roller side cutter 24 is rotatably mounted. Anti-friction roller and ball bearing elements 25, 26 are preferably spaced between each cutter 24 and bearing pin 23, the roller bearings 25 transmitting radial thrusts and the ball bearings 26 both radial and axial thrusts. The ball bearings 26 also retain each cutter 24 on a pin 23, being inserted in place in a passage 27 of the bearing support, which is then closed by a plug 28 welded to the pin. The plug 28 depends from the passage 27 and is used to hold the cutters 24 in retracted position, as explained below.

Each cutter supporting member 19 also includes an upwardly extending arm 29 against which an elastic expander 3i bears. This expander 30, in the form of a compressed coil spring, is received within a retainer pocket 31 in the body and exerts its force against the arm 29, tending to swing it inwardly and thus urge the cutters 24, on the other side of each fulcrum pin 21, in an outward direction. The extent of this outward movement is limited by engagement of a suitable stop shoulder 32 on each cutter supporting member 19 with a cooperable stop portion 32a of the body.

After the cutters 24 have been expanded outwardly by the expander springs 30 to a maximum extent, they can be locked in this position by a tubular member 33 of the mandrel, which it piloted in the kelly 14. This member is provided with a lock portion 34 movable from an upper position in transverse alignment with inner supporting member recesses 35, that allow retraction of the cutters 24, to a lower position opposite lugs 36 formed on and projecting inwardly from the cutter supporting legs 22, which prevent retraction of the cutters.

The tubular member 33 is connected in swivel fashion to the kelly 14, to permit slight relative arcuate or rotary movement therebetween. However, the kelly 14 and tubular member 33 are coupled together for longitudinal movement in both directions. This is accomplished by providing anti-friction thrust bearings between a boss or shoulder 37, fixed on the tubular member 33, and the kelly. The boss is received within a lower socket 38 in the kelly and has a toroidal raceway 39 on its exterior around which a plurality of bearing balls 40 can ride. These balls are also received in opposed toroidal raceways 41 in the kelly.

The balls 40 are insertable into the raceways 39, 41 through a passage 42 extending through the external shoulder 16 on the kelly 14, communicating with its internal race 41. After the balls have thus been disposed ber 33. Fluid pumped down the drill pipe string A will flow through the Kelly pin 12;: and into the central passage 49. It is prevented from flowing around the exterior of the tubular member 33 by asuitable packing Stl disposed between the upper portion 45 of the tubular member and the kelly 14 adjacent the upper end of the tubular member boss 37*.

The arrangement between the tubular member 33 and kelly 14 is such that both downward and upward movement is transmitted between the kelly 14 and tubular member 33 from one raceway 39 or 41, through the ball bearing elements 40, to the other raceway 41 or 39. In this manner, the kellyand tubular member are caused to move jointly in both longitudinal directions, but they are free to partake of relative movement therebetween to allow proper alignment and engagement between the faces 51 on the lock portion 34 and the companion faces 52; on the lugs 36.

When the mandrel 11 and its tubular member 33 are disposed in an upward position relative to the body 15,

to place its lock portion 34, opposite the cutter supporting recesses 35, the cutters 24' and their supporting members 19 may be retained in their inward retracted position against the force exerted by the springs 30. The holding device for accomplishing this purpose includes a holding member 53 secured to the lower end of a central rod 54 whose upper end projects into the tubular member passage 49. A head 55 is secured to the upper end of the rod 54, having substantial clearance in the passage 49 to allow fluid to pass upwardly into the central passage 49 and into the drill string A. The holding member 53 has spaced holes 56. in its outer portion for receiving the lower ends of the ball bearing plugs 28.

When the holding device is disposed over the plug 28, as in Fig. 1, the cutter supporting members 19 are prevented from expanding under the influence of the springs 30, thereby holding the cutters 24 in retracted position. Release of the holding member 53 from the plugs 23 occurs as a result of fluid pressure acting downwardly on the ball 48, which can rest on the head 55, the ball having substantially the same diameter as the passage diameter to allow fluid pressure to be built up in the passage thereabove.

When fluid pressure is applied to the fluid in the drill pipe A and the mandrel passage 49, it can shift the ball 4%, rod 54' and holding member 53 downwardly, to free the latter from the plugs 28 and thereby allow the springs 30 to move the arms 29 inwardly and the cutters 24 outwardly. The drill pipe A and drill bit are rotated, the springs 36 urging the cutters outwardly until they are in their fully expanded position and have produced a formation shoulder E in the wall of the well bore C. Thereafter, downward movement of the mandrel 11 within the body 15 will place the lock portion 34 of the tubular member 33 behind the supporting member lugs 36, to

positively hold the cutters 24 (Fig. 2).

The mandrel 11 will be disposed in its downward position within the body 15', to secure the lock portions 34 behind the lugs 36, so long as downward drilling Weight is being imposed on the tool, with the cutters 24 resting upon the formation shoulder E. In the present instance, it is desired to insure the retention of the lock portion 34 behind the cutter supporting member lugs 36 after the cutters 24. have. been, expanded fully outwardly, despite the elevation of the drill pipe A and the mandrel 11 in the well bore, or in the event drilling weight is no longer being imposed on the, cutters 24. for some, other reason, as the entry of the tool into a cavity in the well bore C. However, despite, the fact that it is desired to hold the lock portions 34 behind the lugs 36, any elevating movement of the mandrel 11, in tools such as described in the aboveridentified patent, resulted in the raising of the mandrel within the body 15, elevating the lock portion 34 above the lugs 36, which allowed the cutters 24 to retract.

in their outward position The retention of the lock. portion 34 behind the cutter supporting member lugs 36., regardless of the elevation of the drill pipe A and the mandrel 11 in the well bore, is achievable in the present instance through the use of a mechanism disposed within the body and mandrel 11 portions of the tool. The tubular member 33 is provided with a mandrel head, external flange or lower spring seat 60 on which the lower end of a helical compression spring 61 rests that encompasses the tubular member. T his compression spring is contanied within a spring housing 62 piloted within the bore 33 of the kelly 14, the upper portion of this spring housing being constituted by an inwardly directed thrust head-, spring seat or flange 63 that engages the upper end of the compression spring 61. The lower portion of the housing 62 is formed integral with a connecting flange 64 resting upon an inwardly directed body shoulder 65, the housing being prevented from moving longitudinally with respect to the body by a plurality of screws 66 threaded into the body 15 and received within a peripheral groove 67 in the housing flange 64.

To facilitate assembly of the apparatus, the boss 37 of the tubular member 33 may be, formed as a separate part suitably secured to the main portion of the tubular member, as through the use of welding material 37a.

When the cutters 24 are locked in their retracted position, such as disclosed in Fig. l, and with the lock portion 34 of the mandrel 33 disposed above the supporting member lugs 36, the spring 61 is in a highly compressed position, being confined within the housing 62 between the housing thrust head 63 and the mandrel thrust head 69. At this time, the spring 61 cannot shift the mandrel 11 in a downward direction, since the locking device 53-56 is holding the cutter supporting members 19 in their inward or retracted positions, the mandrel lock portion 34 engaging the upper portions of the supporting member lugs 36.

When the holding member 53---56 has been released, and the springs have urged the cutter supporting members 19' and the cutters 24 outwardly to their fully expanded position, the compression spring 61 surround ing the tubular member 33 is effective to, in effect, lift the body 15, the cutter supporting members 19 and the cutters 24 upwardly along the mandrel 11 to dispose the lugs 36 fully opposite the lock portion 34 of the tubular member 33. This upward elevating movement is limited by engagement of the lower end 14b of the kelly 14. with the outer flange portion 64 of the spring housing 62. When such engagement occurs, the lock portion 34 of the tubular member is located properly longitudinally along the lugs 36 of the supporting member legs 22 (Fig. 2). The compression spring 61 will retain the parts in the position just described, despite the imposition of drilling weight on the tool or the lack of any drilling weight on the tool. When the lower end 14b of the kelly engages the housing flange 64, the spring 61 cannot shift the mandrel 11 and its tubular member 33 downwardly to any further extent, since the lower mandrel head or spring seat 60 is prevented from moving longitudinally with respect to the Kelly portion 14 of the mandrel by the boss 37 and the interconnecting balls in the boss and Kelly raceways 39, 41.

The parts of the drill bit are disposed in the condition shown in Fig. 1, when the tool is to be run in the well bore, in which the holding member 53 is connected to the cutter plugs 28, the mandrel 11 being in its upward position with respect to the body 15. The compression spring 61, which is exerting a substantial force, is ineffective at this time to shift the mandrel downwardly to its locked position, since the lock portion 34 of the mandrel engages the upper portions of the lugs 36. The tool is attached to the drill pipe A and is lowered through the well casing B. During such lowering action, the fluid in the well bore can pass upwardly into the drill pipe A by flowing around the rod head and through the tool passages 49, 46. At this time, the ball 48 may occupy some upper position above the upper end 47 of the tubular member 33.

ball 48 down into the tubular member passage 49 until it engages the rod head 55. When sufficient pressure is applied, the ball 48 will force the head 55 and rod 54 downwardly, to remove the holding member 53 from the plugs 28, whereupon the coil springs 30 are effective to commerce moving the supporting member arms 29 inwardly and the legs 22 and cutters 24 in an outward direction. The drill pipe A is rotated, the cutters 24 digging into the Wall of the hole C until the cutters have been expanded to their maximum outward position to form the transverse shoulder E in the well bore.

When the cutters 24 have been expanded outwardly to almost their full extent, the upper portions of the lugs 36 are no longer engaging the lower ends of the lock portion 34 of the mandrel 11, so that the compression spring 61 is then effective to shift the mandrel 11 in a downward direction relative to the body 15. The action of the compression spring 61 in shifting the mandrel with respect to the body is a relative one. As a matter of fact, it may actually shift the body 15, and supporting members 19 and cutters 24, in an upward direction. In any event, the compression spring 61 produces the relative downward telescoping action of the mandrel 11 in the body 15, even through downward drilling weight may not, as yet, have been imposed on the drill pipe A, to dispose the lock portion 34 full behind the lugs 36 on the supporting members 19. The compression spring 61 is effective to shift the mandrel 11 downwardly with respect to the body to the extent determined by engagement of the lower end 14b of the kelly 14 with the outer connecting flange 64 of the spring housing 62. When such engagement occurs, the compression spring 61 is still exerting a substantial force on the mandrel 11, tending to hold it in its downward position within the body 15 of the tool.

Downweight may now be imposed on the drill pipe A and the mandrel 11 of the tool, this weight being transmitted through the housing flange 64 to the body shoulder 65, and from the body 15 of the tool to the cutters 24. Rotation of the drill pipe is continued, to cause the hole to be enlarged by reason of the cutters 24 rolling around the formation shoulder E. During this time, the downweight, by itself, is sutficient to hold the lock portion 34 of the mandrel 11 behind the lugs 36, to insure the retention of the cutters 24 in their full outward expanded position. In the event the drill pipe A is elevated, to raise the cutters 24 above the shoulder E, the compression spring 61 exerts sufficient force to also elevate the body 15 with the mandrel 11, the spring 61 acting through the housing 62 to retain the housing flange 64 against the bottom 14b of the mandrel kelly 14.

Inasmuch as the housing 62 is connected to the body 15 through the agency of the screws 66, the body 15 is held in its relative upward position with respect to the mandrel 11. Accordingly, the lock portion 34 of the mandrel is still located completely behind the lugs 36 of the supporting members 19, retaining the cutters 24 in their outward expanded position. If the drill pipe is again lowered and the cutters 24 brought into engagement with the formation shoulder E, assurance is had that the cutters are still fully expanded and that they will immediately recommence drilling a full size hole. The compression spring 61 insures the retention of the mandrel 11 in its full downward position within the body 15, to hold the cutters 24 in their outward expanded positions, no movement of the mandrel 11 with respect to the body 15 occurring during the raising of the cutters 24 above the formation shoulder E, or their relowering into engagement with this formation shoulder. In effect,

. if the tool were to be inwardly and the lower ends of the parts of the bit remain in their position disclosed in Fig. 2, with cutters held outwardly expanded.

The foregoing condition described in connection with the elevation of the drill pipe A would also be presented lowered into a cavity (not shown) in the well bore C. Such action would eliminate the drilling weight on the cutters 24, but the compression spring 61 would still be effective to hold the body 15 to its fullest extent in a relative upward position along the mandrel 11, with the housing flange 64 remaining in engagement with the lower end 14b of the kelly 14. Accordingly, the cutters 24 remain locked in an outward expanded position and cannot retract even partially, an act which could occur if the body 15 of the tool were allowed to drop down with respect to the mandrel 11. Such dropping action would be permissible if a device like the compression spring 61 were omitted.

In the event it is desired to remove the tool from the well bore, the drill pipe A is elevated, the cutters 24 remaining in their outward expanded position so long as they are disposed in the enlarged diameter portion of the well bore. Should they be moved into an upper restricted diameter portion, or into engagement with the casing shoe D, the further elevation of the cutters 24 would be prevented momentarily. However, an up ward pull taken on the drill pipe A then elevates the mandrel 11 within the body 15 against the compressive force of the spring 61, since the body 15 cannot move upwardly at this time. The spring 61 is further compressed and shortened in length by the upward movement of the mandrel 11 within the body, the lock portion 34 of the tubular member being moved up above the lugs 36 and opposite the recesses 35. This allows the wall of the restricted diameter well bore or the casing shoe D to act upon the outer surfaces of the supporting members 19, to shift the latter inwardly against the force of the expander springs 30 and carry the cutters 24 inwardly to their initial or normally retracted position. The supporting members 19 and cutters 24 can then be pulled completely within the well casing B and will remain in such retracted position, the outer surfaces of the supporting members 19 merely riding along the wall of the well casing. During this time, the compression spring 61 is ineffective to shift the lock portion 34 relatively downward with respect to the lugs 36, since the wall of the well casing B is holding the cutter supporting members 19 the lock portion 34 can do nothing more than bear against the upper ends of the lugs 36 (as in Fig. l). The tool can be elevated by the drill pipe A in the well casing B until it is completely withdrawn from the well bore at the top of the hole.

It is, accordingly, apparent that a rotary expansible drill bit has been provided in which the cutters are positively locked in their outward position by the downward telescoping movement of the mandrel with respect to the body. The mandrel is normally held in this downward position, even in the absence of drilling weight being imposed on the cutters, by the compression spring 6 device 6067 acting between the body 15 of the tool and the mandrel 11. Despite such holding action of the c0mpression spring device, it still does not interfere with the unlocking of the tool and the reshifting of the cutters to their retracted position relative to the body of the tool when the latter is to be withdrawn from the well bore.

The inventor claims:

1. A rotary drill bit, including a main body, cutter means mounted on said body for expansion laterally outward of said body, means for expanding and holding said cutter means laterally outward, said expanding and holding means comprising a mandrel having an upper connection for securing said mandrel directly to a drill string, said mandrel being slidably splined to said body, whereby torque is transmitted from the drill string to said mandrel and from said mandrel to said body, said mandrel being movable relatively downward of said body to hold said cutter means laterally outward, and compression spring. means. engaging said mandrel and body to urge. said mandrel relatively downward of said body to a position holding said cutter means laterally outward.

2. A rotary drill bit, including a main body, cutter means mounted on said body, means engaging said cutter means for expanding said cutter means laterally outward of said body, a mandrel having an upper connection for securing said mandrel directly to a drill string, said mandrel being slidably splined to said body whereby torque is transmitted from the drill string to said mandrel and from said mandrel to. said body, said mandrel including a portion movable in one longitudinal direction relative to said body into engagement with said cutter means to prevent inward movement of said cutter means from its outwardly expanded position, and compression spring means engaging said body and mandrel to urge said mandrel portion relative to said body in said one longitudinal direction to the. position in which said portion holds said cutter means laterally outward.

3Q A rotary well drilling bit, including a main body, cutter means mounted on said body, means engaging said cutter means for. expanding said cutter means laterally outward of said body, a mandrel having an upper connection for securing said mandrel directly to a drill string, said mandrel being slidably splined to said body, whereby torque. is transmitted from the drill string to said mandrel and from said mandrel to said body, said mandrel including a portion movable downwardly relative to said body into engagement with said cutter means to prevent inward movement of said cutter means from its outwardly expanded position, and compression spring means engaging said body and mandrel to urge said mandrel portion downwardly relative to said body to the position in which said mandrel portion holds said cutter means laterally outward.

4. A rotary drill bit, including a main body, cutter means mounted on said body for expansion laterally outward of said body, means for expanding and holding said cutter means laterally outward, said expanding and holding means comprising a mandrel having an upper connection for securing said mandrel directly to a drill string, said mandrel beingslidably spiined to said body whereby torque is transmitted from the drill string to said mandrel and from said mandrel to said body, said mandrel being movable. relatively downward of said body to hold said cutter means laterally outward, a spring retainer secured to said, body, and a compression spring having its upper portion bearing upon said retainer and its lower portion against said mandrel to urge said mandrel relatively downward of said body to a position holding said cutter means lateral-1y outward.

5. A rotary well drilling bit, including a main body, cutter means mounted on said body, means engaging said cutter means. for expanding said cutter means laterally outward of said body, a mandrel having an upper connection for securing said mandrel directly to a drill string, said mandrel being slidably splined to said body, whereby torque is transmitted from the drill string to said mandrel and from said mandrel to said body, said mandrel including a portion movable downwardly relative to said body into engagement with said cutter means to prevent. inward.- movement of said cutter means from its outwardly expanded position, a spring retainer secured to said body, and a compression spring having its upper portion bearing upon. said retainer and its lower portion against said mandrel to urge said mandrel relatively downward of said body to the position in which said mandrel portion holds said cutter means laterally outward.

6. A rotary drill bit, including a main body, cutter means mounted on. said body for expansion laterally outward ofsaid body, means for expanding and holding said cutter means. laterally outward, said expanding and holding means comprising a mandrel having an upper connecion for securing said mandrel directly to a drill string, said mandrel being slidably splined to said body, said mandrel being movable, relatively downward of said body to hold said cutter means. laterally outward, a spring housing secured to said body, and a compression spring within said housing and encompassing said mandrel, the upper portion of said spring bearing against said housing and the lower portion of said spring bearing against said mandrel to urge said mandrel relatively downward of said body to a position holding said cutter means laterally outward.

7'. A rotary well drilling bit, including a main body, cutter means mounted on said body, means engaging said cutter means for expanding said cutter means laterally outward of said body, a mandrel having an upper connection for'securing said mandrel directly to a drill string, said mandrel being slidab'ly splined to said. body, said mandrel including a portion movable downwardly relative to said body into engagement. with said cutter means to prevent inward movement of said cutter means from its outwardly expanded position, a spring housing secured to said body, and a compression spring within said housing and encompassing said mandrel, the upper portion of said spring bearing against said housing and the lower portion of said springbearing against said mandrel to urge said mandrel relatively downward of said body to the position in which said mandrel portion holds said cutter means laterally outward.

8. A rotary well drilling bit, including a main body, cutter means mounted on said body, means engaging said cutter means for expanding said cutter means laterally outward of said body, a mandrel connectible to a drill string and slidably. splined to said body, said mandrel including a portion. movable downwardly relative to said body into engagement with said cutter means to prevent inward movement of said cutter means from its outwardly expanded. position, a spring housing secured to said body and having a spring seat, said mandrel having a spring seat below said housing seat, and a compression spring within said housing and encompassing said mandrel between said seats, said spring bearing against both of said seats to urge said mandrel relatively downward of said body.

Dunham Sept. 1, 1925 Kammerer Mar. 13, 1951 

